Research On N-phenylglycinonitrile Wastewater Treatment By Physical Chemistry And Bio-chemistry Process

The n-phenylglycinonitrile chemical wastewater is a kind of high concentration of refractory organic wastewater . Experiment study on the wastewater treatment was introduced in this paper.To find a proper approach to purify the wastewater , pre-treatment experiment study was adopted . In the pre-treatment experiment , absorption , Fe-C micro-electrolysis , alkaline hydrolysis and still standing crystallization were applied in treating the wastewater . The results showed that the first three pre-treatment experiments were not very efficiently . The removal efficiency of COD was not high , furthermore , with the last two pre-treatment methods , the effluents were roily , which was disadvantageous to the bio-chemical process of subsequent treatment . Still standing crystallization was high COD removing , low running cost , and recoving product , so still standing crystallization was adopted . The COD of the raw wastewater was diluted to about 2000mg/L , which was used to inoculate sludge from municipal sewage treatment plant . The process was anoxic-SBR , and PAC was dropped into SBR tanks . The test was successful . The COD of effluent stabilized about 200mg/L . After success in the laboratory , the process was expanded to full-scale test . During the full-scale test , the sludge was acclimatized by two-stage aerobic process , thus the sludge grew quickly . After the acclimatization succeeding , the process was changed to anoxic-SBR . The DO was controlled below 1mg/L in anoxic system , and 2 to 4mg/L in aerobic system . The raw wastewater was diluted by cyclic water . When the COD of influent was about 3000mg/L , the COD of effluent was about 300mg/L . The NH3-N was about 40 to 50mg/L after stripping. The effluent of stripping can reach to the requirements as cooling water . This process was run by means of closed cycle . The effluent of stripping was back into the cyclic water tank , which was reused as cooling water after national degradation .The process had no sludge treatment system , which simplified the operation , and decreased the running cost obviously . During the full-scale test , the running cost was 12.4 Yuan per cubic meter or 0.50 Yuan per kilogram COD removal.